"sharp as a tack" meaning in English

{
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "sharp as a tack (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English similes",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1999, Tina Koch et al., Still Me, Wakefield Press, page 148",
          "text": "When Mum died at ninety she was still as sharp as a tack. Everything else wore out.",
          "type": "quotation"
        },
        {
          "ref": "2005, David E. Talbert, Love on the Dotted Line, page 12",
          "text": "But Ophelia was smart. Sharp as a tack. Everybody in the firm knew it.",
          "type": "quotation"
        },
        {
          "ref": "2021 May 17, Jane E. Brody, “A Birthday Milestone: Turning 80!”, in The New York Times, →ISSN",
          "text": "Dr. Anthony Fauci, national infectious disease guru, is five months my senior, sharp as a tack even under withering political fire;",
          "type": "quotation"
        }
      ],
      "glosses": [
        "very intelligent"
      ],
      "id": "en-sharp_as_a_tack-en-adj-aClCmXYU",
      "links": [
        [
          "very",
          "very"
        ],
        [
          "intelligent",
          "intelligent"
        ]
      ],
      "qualifier": "simile",
      "raw_glosses": [
        "(simile, colloquial) very intelligent"
      ],
      "related": [
        {
          "word": "not the sharpest tool in the box"
        }
      ],
      "synonyms": [
        {
          "word": "intelligent"
        }
      ],
      "tags": [
        "colloquial",
        "not-comparable"
      ],
      "translations": [
        {
          "code": "hu",
          "lang": "Hungarian",
          "sense": "very intelligent",
          "word": "vág az esze, mint a borotva"
        },
        {
          "code": "es",
          "lang": "Spanish",
          "sense": "very intelligent",
          "word": "más listo que el hambre"
        }
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-au-sharp as a tack.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/9/98/En-au-sharp_as_a_tack.ogg/En-au-sharp_as_a_tack.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/9/98/En-au-sharp_as_a_tack.ogg",
      "tags": [
        "Australia"
      ],
      "text": "Audio (AU)"
    }
  ],
  "word": "sharp as a tack"
}

{
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "sharp as a tack (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "related": [
    {
      "word": "not the sharpest tool in the box"
    }
  ],
  "senses": [
    {
      "categories": [
        "English adjectives",
        "English colloquialisms",
        "English lemmas",
        "English multiword terms",
        "English similes",
        "English terms with audio links",
        "English terms with quotations",
        "English uncomparable adjectives"
      ],
      "examples": [
        {
          "ref": "1999, Tina Koch et al., Still Me, Wakefield Press, page 148",
          "text": "When Mum died at ninety she was still as sharp as a tack. Everything else wore out.",
          "type": "quotation"
        },
        {
          "ref": "2005, David E. Talbert, Love on the Dotted Line, page 12",
          "text": "But Ophelia was smart. Sharp as a tack. Everybody in the firm knew it.",
          "type": "quotation"
        },
        {
          "ref": "2021 May 17, Jane E. Brody, “A Birthday Milestone: Turning 80!”, in The New York Times, →ISSN",
          "text": "Dr. Anthony Fauci, national infectious disease guru, is five months my senior, sharp as a tack even under withering political fire;",
          "type": "quotation"
        }
      ],
      "glosses": [
        "very intelligent"
      ],
      "links": [
        [
          "very",
          "very"
        ],
        [
          "intelligent",
          "intelligent"
        ]
      ],
      "qualifier": "simile",
      "raw_glosses": [
        "(simile, colloquial) very intelligent"
      ],
      "synonyms": [
        {
          "word": "intelligent"
        }
      ],
      "tags": [
        "colloquial",
        "not-comparable"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-au-sharp as a tack.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/9/98/En-au-sharp_as_a_tack.ogg/En-au-sharp_as_a_tack.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/9/98/En-au-sharp_as_a_tack.ogg",
      "tags": [
        "Australia"
      ],
      "text": "Audio (AU)"
    }
  ],
  "translations": [
    {
      "code": "hu",
      "lang": "Hungarian",
      "sense": "very intelligent",
      "word": "vág az esze, mint a borotva"
    },
    {
      "code": "es",
      "lang": "Spanish",
      "sense": "very intelligent",
      "word": "más listo que el hambre"
    }
  ],
  "word": "sharp as a tack"
}